D-dot and B-dot monitors for Z-vacuum section power-flow measurements

New differential D-dot and B-dot monitors were developed for the Z vacuum section of an accelerator pulsed power supply. The D-dots measure voltage at the insulator stack. The B-dots measure current at the stack and in the outer magnetically-insulated transmission lines. Each monitor has two outputs that allow common-mode noise to be cancelled to the first order. The differential D-dot has one signal and one noise channel; the differential B-dot has two signal channels with opposite polarities. Each of the two B-dot sensors in the differential B-dot monitor has four 3 mm diameter loops and is encased in copper to reduce flux penetration. For both types of probes, two 2.2 mm diameter coaxial cables connect the outputs to a Prodyn balun for common-mode-noise rejection. The cables provide reasonable bandwidth and generate acceptable levels of Compton drive in the bremsstrahlung field of the Z accelerator. A new cavity B-dot is being developed to measure the total Z current 4.3 cm from the axis of the z-pinch load. All of the sensors are calibrated with 2-4% accuracy. The monitor signals are reduced with Barth or Weinschel attenuators, recorded on Tektronix 0.5 ns/sample digitizing oscilloscopes, and software cable compensated and integrated.